The present invention relates to an indicator system which advises an operator or driver of the deflation of one or more pneumatic tires on a wheeled vehicle, and more particularly, in certain aspects, an indication device comprising a road-surface-contacting probe, which when engaged, activates an alarm to warn an operator or driver of a deflating tire.
This invention was the subject of U.S. Patent Office Disclosure Document Number 461610, filed Sep. 5, 1999, entitled, LOW-TIRE INDICATOR FOR WHEELED VEHICLES.
Most wheeled vehicles on the road today employ pneumatically-inflated tires. Although tubeless pneumatic tires are superior to former tube-type pneumatic tires in many respects, tubeless pneumatic tires develop slow leaks and, when a complete tire failure occurs, deflate more quickly. Because the seal between the wheel rim and tire may be incomplete, due to deformation of the wheel rim or imperfections or deformations in the tire, air leaks from the tire.
Pneumatic tires require proper inflation to support the vehicle in transport. Proper inflation is required for evenly distributing the wear and heat suffered by a tire in the course of travel along a road. In the course of travel along a road, the shape of a tire changes: the shape of the tread changes as a tire rolls on a road surface; as the tread changes shape in its contact and departure from the road surface, the tire walls flex. As the walls of a tire flex, the seal between the rim of the wheel and the pneumatic tire can be compromised, thus causing a loss of air pressure within the tire. As the air pressure decreases, the flexing of the tire worsens. While a certain flexing at proper-operation air pressure is contemplated when a tire is designed, excessive flexing of the tire shape generates excessive heat and wears excessively tire components. Excessive heat and wear can cause tire deflation or failure. As a tire loses air pressure or fails altogether, the height of the tire diminishes, and the distance the vehicle or trailer rides above the road also decreases.
Vehicles can be, and are, operated with one or more of the pneumatic tires in a deflated position without the driver of the vehicle being aware of the danger caused by the deflated tire condition. Furthermore, it is common for vehicles to have multiple sets of tires with varying loads, capacities and pressures according to the demands upon the vehicle involved.
As a result of these conditions, the deflation, degradation and catastrophic loss of air pressurexe2x80x94a blow outxe2x80x94of tire are common, although dangerous, events. When a complete tire failure occurs, various vehicle components, including the tire itself, wheel rim, assembly and vehicle body components can be damaged. Frequently, when a tire fails, the undercarriage or body of the trailer falls and is dragged, and the resulting damage is generally very expensive. The resulting damage to the vehicle and trailer can be extreme and entail large repair expense. It is also frequently the case that when one tire fails, the weight on a second tire exceeds its weight limit and causes a failure as well. In that case, the damage to an entire side of a trailer can be occasioned. Furthermore, the driving hazard associated with towingxe2x80x94then draggingxe2x80x94a trailer with one or more tire failures at cruising speeds is a road safety hazard, not only to the towing vehicle and its occupants, but to the other motorists and vehicles on the road.
Thus, proper inflation of the tires affects not only the performance, but the longevity of the trailers, tractors, trucks or passenger vehicles and, foremost, the safety of travel.
Because the driver of the towing vehicle is usually unable to easily ascertain when the trailer has suffered a blow-out or whether a tire has lost air pressure, the need exists for a low-tire pressure warning system which may be readily mounted on various forms of vehicles to indicate to an operator when one of the pneumatic tires has become deflated or failed. Until this invention, there was no similar cost-effective apparatus which remotely monitors tire pressure by measuring the elevation of a vehicle or its trailer while in transit.
Low-tire warning systems and structures in certain prior art embodiments describe and claim specific structures.
U.S. Pat. No. 5,583,481 (Gardner) describes a low-tire warning system with a rod which is mounted in a rubber insulator. When a tire deflates, the electrical spring actuator (27), as part of the sensor switch, bends and contacts an exposed metallic cylinder thus closing the switch and completing an electric alarm circuit. Furthermore, the claims of the Gardner patent cover only two lights on the panelxe2x80x94one to indicate that the system is on and the second to apprise the operator that a tirexe2x80x94and not which tirexe2x80x94is deflated.
U.S. Pat. No. 5,327,116 (Davidson) describes a low-tire detection device with specific structural elements, notably the ground-contacting resilient sensor rod (32). The claims specifically identify that the initial position of the probe is biased forward at a slight angle to the vertical in the direction of movement of the tire. Furthermore, the flex contact (68) of the electrical control switch (64) is directly engaged by the rotary motion of the rod (32).
U.S. Pat. No. 5,032,822 (Sweet) describes a tire deflation warning system with specific structural elements, notably a vertically disposed post. As a tire deflates, wheels (30) at the end of the post contacts the road surface (13), the post should move upward, and a pedestal contacts an activator means to complete an electrical circuit, thus activating an alarm. The only rotary motion described is by the wheels (30); otherwise, the actuation of the alarm is effected by vertical motion of the elements of the invention.
U.S. Pat. No. 4,187,495 (Mitchell) is a low tire pressure warning system which features a laterally-deflecting probe, identified as wobble actuator (14) to detect a lateral protuberance in a deflated tire. As the tire pressure decreases, the lateral protuberance expands thus contacting the wobble switch actuator (14). The wobble switch actuator (14), in turn, as a part of the switch, closes the electrical circuit and engages the audible signal generator (26).
U.S. Pat. No. 3,413,598 (Uphoff) employs a probe which contacts the road, bends backwards, and one end of the probe engages the push-switch to activate the alarm.
U.S. Pat. No. 2,258,334 (Miller) describes a probe, one end of which is part of the switch encased in an insulating material. When the probe is flexed, one end of the probe moves to close the electrical circuit. The cup-shaped bracket and the use of the large insulated leg also serve as the flexing component.
U.S. Pat. No. 2,191,205 (Rogers) employs a leg, mounted by a pivot onto a bracket. When the downwardly-extending leg is moved, a pivotally-mounted arm moves to close the electrical switch contact.
Some prior patent art suggests that a probe element that points forward into the general direction of travel is preferable, but in a catastrophic loss of tire pressure or the instantaneous destruction of the tire, it is possible for the forward-pointing probe to ride along the travelling surface, thus not rotating to engage the switching element and alarm; thus, failing to inform the operator of the tire failure while further damage ensues.
Some prior patent art uses its probe element to measure the lateral displacement of the bulge at or near the travelling surface in contact with the pneumatic tire caused by a loss of air pressure. A tire may have lateral motion due to reasons other than loss of air pressure; furthermore, a blown out tire will have no lateral bulge to measure at all.
Additionally, the prior art teaches that the probe, be it a ground-contacting or tire-contacting element, directly engages the switch or is an element that completes the electrical circuit. The probe is subjected to a wide variety of harsh forces; in the prior art, the electrical switching elements are therefore subjected to the abrupt and destructive forces the ground-contacting element suffers.
The present invention relates to an indicator which advises an operator or driver of the deflation of a tire on a wheeled vehicle, and more particularly, in certain aspects, an indication device consisting of a road-surface-contacting probe, which when engaged, activates an alarm to warn an operator or driver of a malfunctioning tire.
This invention, entitled a low-tire indicator for wheeled vehicles, comprises: (1) a probe element with a first end and a second end; (2) a shaft, with a first end and a second end, the first end of the shaft being attached the first end of the probe; (3) a bracket, attached to the second end of the shaft; (4) an electrical switching element mounted upon the bracket; (5) a cap, with an interior and an aperture, which aperture holds the shaft between the first end of the shaft and the second end of the shaft; (6) at least one retaining element attached to either the interior of the cap or the interior of the housing for engaging the bracket and electrical switching element; (7) a housing, with an interior, an exterior, a mounting base and a cap-receiving opening, upon which cap receiving opening the cap is mounted and in which interior the electrical switching element, bracket and at least one retaining element are housed and upon which mounting base an attachment to the axle or other component of a vehicle or trailer is made; and, (8) an alarm electrically attached to the switching element.
The main object of this invention is to provide a low-pressure warning system including visual and audible signal generators actuated in response to the sensing of low tire pressure.
A further object of this invention is to provide a low tire pressure warning system which may be utilized on operator-driven vehicles as well as on vehicles trailed behind operator-driven vehicles.
A further object of this invention to provide a system in accordance with the preceding objects readily adapted for use on vehicles having tires of different sizes.
A further object of this invention is to provide a low tire pressure warning system which may be easily installed on to various forms of vehicles after their manufacture.
A further object of this invention is to provide a low tire pressure warning system of simple, durable construction and operation amenable to low-cost manufacture.
These and other objects and advantages of the present invention, as well as details of the preferred embodiment thereof will be more fully understood from the following description and the drawings.